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Use of speed brakes in flight

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Old 23rd Jul 2008, 20:14
  #41 (permalink)  
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Top marks that man! I did it on purpose and made the mistake intentionally out of respect for the many Ppruners here who appear to think that is the way what it is done! I italicised it to give a clue, but it seems to be what they teach in schools these days!
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Old 23rd Jul 2008, 20:16
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Ah I thought as much!

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Old 24th Jul 2008, 01:12
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Not mentioned so far (unless I missed it) is the use of split spoilers for pitch control in the event of stab problems...jammed in the cruise position, for example.
Personally used this twice on the 'ole 707...very handy to have this facility, so you don't have to strong-arm the pole...or even worse, run out of elevator authority.
Or, on takeoff.
DAL had quite a nasty incident with one of their L1011's, when the elevators remained in the full nose-up position after the normal control check (elevators mechanically linked to the all-flying stab) at KSAN.
So, split the spoilers (all off except 1&2 inboard panels), then use the spoiler lever to get the nose down.
Very handy, indeed.
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Old 24th Jul 2008, 01:52
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Hello Colin

Seems that you like Airbus aircraft, so here are some interesting facts related to speebrake use in the A320 family.

*(A320) With autopilot on, the maximum deflection will be achieved when you put the speedbrake lever at the "1/2" position. Even if the lever is at the "Full", the system won't allow you go further than half.
Although you have limited authority, it's just fine for most STAR's and ATC requests.
For full speedbrake deflection, you'll need to disconnect the autopilot.

*Speedbrake will retract automatically if one of the below conditions occur:
1- Flaps at FULL (3 and FULL for the A321)
2- Thrust levers above the MCT detent
3- Alpha Floor activation
4- Angle of Attack protection active (...and much more!)

This is extremely useful in a GPWS "Pull Up" call, for example. When you apply TOGA, the speedbrake will retract (although the memory item asks for you to check the speedbrake lever in the retracted position!)

Hope you enjoy it
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Old 24th Jul 2008, 09:45
  #45 (permalink)  
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I would again like to thank you very much.

Antunes I liked you're rather informative and educating reply. May I ask however what is Alpha Floor activation?

Thank you
Colin.
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Old 24th Jul 2008, 09:59
  #46 (permalink)  
 
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Just to momentarily go back to the original question (by the way - I have never used speed brakes, reverse thrust or wheel brakes - it all stinks of poor energy management to me!!) - Long ago when I flew the Tucano, some airframes did have a 250kt restriction on the 'air-brake' (as it was called then!) and with a Vne of 300kts it always seemed quite strange that you had to wait to slow down to be able to use speed brake. I believe this was a structural limit on the actuator mechanism which was straining and bending under the hgh loading at faster speeds. In time they were upgraded and I think that they now all have a 300kt limit.
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Old 24th Jul 2008, 10:10
  #47 (permalink)  
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I really hope you are not "waving your rolled up newspaper about" and "putting the gear down for a final plunge" all at the same time...it could all get rather messy. Sorry, I come from the..if you need 'em use'em school, thats why they are there. And its better to be a little low early and stabalised, than high and fast......

standing by for incoming.....
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Old 25th Jul 2008, 18:04
  #48 (permalink)  
 
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If you need 'em use 'em, and those of us who fly into the good Ole US of A need them an awful lot

Those old salty dogs in the left seat who advocate a rolled up newspaper...would get from me, a nice short left jab in return...
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Old 25th Jul 2008, 20:07
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The only time you use "speed brakes" is in flight.
When used on the ground they are called "spoilers"

(I'm just messin with your mind)
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Old 25th Jul 2008, 20:50
  #50 (permalink)  
 
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Whilst I read the Airbus will auto stow the speedbrakes with thrust above MCT.
I believe the B767 will not...
Because of the potential danger of reduced climb performance caused by this design feature in an attempted goard or pull up manouver requireing full power... the Gf SOPs for the 767 in my day required the handling pilot to always keep his hand attached to the speedbrake lever if he was useing speedbrake until he restowed the speedbrake lever totally... then he could let go of it. Partial speed brake was not to be used...smoothly use the lot or not at all..was also GF SOP.
The general idea was I believe to avoid the full application of thrust ever being used with the speedbrakes deployed fully or even partially with a steep climb being wanted...i.e. You were never to forget speedbrakes were deployed and would not auto restow.
I think the AA pilots B767 at Cali unfortunately ended up in this undesireable configuration...after being offered and deciding to accept the ATC option to change their minds to a shortend track miles to touchdown straight in approach...they had previously planned and briefed for a more gentle overhead procedure as published on the approach plate.
Probably they thought they had a valid reason to brief for one approach and then attempt another at short notice....they fully deployed the speedbrakes to increase the aircraft rate of descent at night into a high terrain area to try and achieve this new approach descent profile and it appears they left the speedbrakes deployed until they crashed... they were also not really sure of their exact position when asked by ATC... later attempting an escape manouvre they hit the hills I believe with power fully on..nose pitched up...speedbrakes fully deployed..then their luck ran out.
Regarding L1011 DLC....I was told DLC had to be fitted because it was desireable the aircraft retained the Glideslope with a constant pitch attitude and provided a consistant pilot runway picture on a visual approach and a constant point of reference when looking for the runway in LVP.
If I remember correctly there was a required pilots seat back angle and position on landings and also a pilot eye locater devise to ensure a consistant view to both pilots...it also helped them to reach nearly all of the knobs and switches they might need.
DLC was also required to ensure the L1011 would land within the limits require for auto land certification at the correct autoland runway touchdown point.
Monitoring and ensuring the correct ADI pitch attitude on the glidescope was important to L1011 pilots.
On an autoland approach an Auto throttle drive failure was not announced as a failure to the pilots or flight engineer... and had to be picked up by crew monitoring.
With an Auto throttle drive failure the glide slope was retained by the coupled auto pilot and the pitch attitude would slowly and silently increase and the IAS would slowly then not so slowly bleed off...if this situation was not noticed and immediatly corrected with positive manual power application and the correct pitch attitude and speed regained or a goard performed you would next see an alpha flag and next a stall warning which might wake you up...if not Gf SOP was... the flight engineer gave you full power... the f/o pressed toga and manually flew the aircraft to a safe MSA..
In this situation GF SOPS (as ammended) required the flight service supervisor (female if you were lucky) to immediately enter the cockpit useing her axcess key... and bite the end off the Captains cock...and to inform the Captain that this service was on behalf of GF ops. management for being such a piss poor Captain..... National Captains as you would expect got a blow job... and a promotion for handling the situation so well.
A L1011 manual or autoland landing attempt with a pitch up attitude of I believe more than 11degrees was likely to result in an expensive tail strike
and a revisit from the flight service supervisor.

Last edited by 40&80; 25th Jul 2008 at 21:42.
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Old 25th Jul 2008, 21:26
  #51 (permalink)  
 
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Regarding L1011 DLC....I was told DLC had to be fitted because it was desireable the aircraft retained the Glideslope with a constant pitch attitude and provided a consistant pilot runway picture on a visual approach and a constant point of reference when looking for the runway in LVP.
If I remember correctly there was a required pilots seat back angle and position on landings and also a pilot eye locater devise to ensure a consistant view to both pilots...it also helped them to reach nearly all of the knobs and switches they might need.
DLC was also required to ensure the L1011 would land within the limits require for auto land certification at the correct autoland runway touchdown point.
Monitoring and ensuring the correct ADI pitch attitude on the glidescope was important to L1011 pilots.
On an autoland approach an Auto throttle drive failure was not announced as a failure to the pilots or flight engineer... and had to picked up by crew monitoring.
With an Auto throttle drive failure the glide slope was retained by the coupled auto pilot and the pitch attitude would slowly and silently increase and the IAS would slowly then not so slowly bleed off...in this situation was not noticed and immediatly corrected with positive manual power application and the correct pitch attitude and speed regained or a goard performed you would next an alpha flag and next a stall warning...a manual or autoland landing attempt with a pitch up attitude of I believe more than 11degrees was likely to result in an expensive tail strike.
I last flew the L1011 in Jan 1989 so all I say is probably all full of **** as my memory is nearly time ex.
Nothing wrong with your memory...all generally correct.
DLC enabled the L1011 to be CATIIIB certified, right out of the factory...not done later, as with other earlier designs.

However, it was always amusing to watch a new TriStar pilot attempt the 'Boeing push' for an extra smooth landing.
Ha!
The resulting thud would knock you back teeth loose...good thing Lockheed bolted the wings on really tight for these ex-Boeing guys.
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Old 27th Jul 2008, 07:05
  #52 (permalink)  
 
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Wink

RB

and being a fuel miser....which is what I am, out of duty to my employer's bottom line..........................
Bit of a fuel miser myself, but out of pure self interest, not a sense of company loyalty.

When I execute the missed approach, I want the maximum available fuel for the hold / divert.

Can never understand the guys that are lazy about saving fuel, because 'the company doesn't give a sh&t about me"!

Of course, if it helps the company survive through to another pay day, it's a bonus!





Snooze
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Old 27th Jul 2008, 08:00
  #53 (permalink)  
 
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Just to add a different twist...

On a glider the Air Brakes fitted to the wing operate slightly differently. They still reduce lift and increase drag but aren't normally used to the control speed or perhaps I should say they aren't directly used to control speed. Typically on approach the speed is set using elevator then the air brake is used to adjust the glide angle.

In an ideal landing the glider would be flown (using good planning) into a position where about half air brake can be used all the way down final. If you find you are using all or none then basically you got it wrong. If you find you need all the brake it means you started too high or over estimated the wind speed - and you risk an overshoot. If you find you need no brake then you were too low or you under estimated the wind - and risk an undershoot.
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Old 27th Jul 2008, 09:36
  #54 (permalink)  
 
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Speedbrake = Capts precision planning device and Co- Pilots bad planning device....

Into London this morning; 25 Nm then 20 Nm to go from ATC then instruction turn left onto base leg - Boss`s name is now "Heinz" as he obviously used to fly Stuka`s! Did he use the speedbrake? You betcha

Used all that other drag stuff as well, wheels flaps etc.....
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Old 27th Jul 2008, 10:48
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Think it was alluded to earlier in this thread about the A320 series but the 777 is very hard to slow onceon the glideslope and almost always requires speedbrakes to slow 180/160kts etc.
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Old 27th Jul 2008, 11:35
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IMHO Rainboe's position on use / misuse of speedbrakes is spot-on.

They are (in my company) used far far too often, and usually unnecessarily/incorrectly. Many pilots use them on every sector, sometimes several times. This is far too often if proper descent planning and judgement are used.

As RB said, use of speedbrake in intermediate descent where a level sector is to follow is usually a sign of incorrect entry point for that descent, and a slight speed adjustment will often sort that out without shaking the airframe and scaring some of the pax with the vibration. It is a much kinder and smoother way to achieve the same thing, but no, most just dive for the mistake handle. Use of speedbrake followed by an increase in power is, as RB said, often a very questionable procedure.

Pavlovian use of sb whenever the indicator says above profile is another common fault. It happens on a daily basis and is almost always unnecessary, and avoidable by a bit of thought of what lies ahead.

They are sometimes used like brakes on a car for speed reductions in level flight! (followed by a power increase, of course...) This is all just evidence of poor planning and awareness.

On the 737 it is virtually useless below 250Kts anyway, and Mr Boeing recommends it is NOT USED in conjunction with flaps. So why use a control that won't help you, that compromises controlability, that stresses the airframe and pax and that the manufacturer recommends you don't use in this scenario when you can put the wheels down a few seconds earlier than usual? "Non standard, gear down" solves the problem, unless you are so stuck in your SOPs that you just can't fly the aeroplane...It also has the advantage that it works, because if significantly high at this stage the sb's extra 200fpm won't help you anyway, and the minute or so it will take to become obvious just brings the aircraft ever higher and closer in, requiring ever more drastic action to correct.

There are many ways to skin a cat, as there are many ways to get an aeroplane to descend faster. Some are neater, more comfortable and more Proessional than others. You don't have to use the sb every time.

A bit of thought would prevent 75% of use of speedbrakes. IMHO, of course!

And finally, if you must use them, for God's sake use them smoothly and gently. They can cause the most sickening lurches when handled clumsily - which happens all too often, sadly. But then all too often pilots seem blissfully unaware that there are pax behind them who are very aware of jerky, uncomfortable flying.

(Same goes for wheel braking, but that is another topic entirely)

Last edited by Agaricus bisporus; 27th Jul 2008 at 11:50.
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Old 27th Jul 2008, 11:57
  #57 (permalink)  
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Agreed, AB - I think the only difference you and I have with RB is the use of a rolled-up Daily Mail? I normally gently 'stay' the grabbing hand and say - why? Generally a light then comes on in the head and another way is thought of. There must be some Captains who always grab for the s/b in order to instill such 'automatic' reactions? Could it be as simple as Boeing's message 'Drag required'?

Incidentally, BA (used to, up to 2004 anyway) impose NO limits on s/b with flap on the 737, right up to Flap40, merely not below 1000'. I have personally experienced it used at Flap30 by a BA 737 captain (only briefly, I should add). The biggest structural danger IMO is the tailplane buffet.
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Old 27th Jul 2008, 18:08
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BOAC, you are spot-on, as usual.

Use of the Daily mail as described by Rainboe is shameful in this day and age. I am disgusted that there are still Captains around with such appalling CRM as to beat studes with the Mail instead of the Telegraph, which, apart from being factual and useful is also being bigger and heavier and thus so much more effective. The "CRM" displayed by Captains who read the Mail is best left unsaid.

God bless Sqn Ldr Gell RAF who introduced me to this valuable technique, though it could be a trifle disorientating half way around a loop...
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Old 27th Jul 2008, 18:30
  #59 (permalink)  
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The use of a rolled up newspaper is excellent for 'imprinting' what one is trying to get over. Indeed, being a former inmate of a boarding school, I positively need this to remember. I even asked my simulator instructor to use just this item on my recent conversion course to the 757 as after enormous years of 747 and 737 and other aeroplanes that refer to engines as 1, 2, 3&4 (I'm showing off with the last group there), I now have to fly a bloody aeroplane that refers to them as 'Left' and 'Right' for some weird reason. I was unable to ditch the habit in an emergency, a swear box fine didn't work, so I requested a rolled up newspaper on the back of the head, just as I was given so much in my youth! It took 10 sessions to sink in.
Quite apart from limited ability descent planning upsetting me, I am REALLY upset at some of the appalling CDAs the young chaps come out with, thinking what a jolly good job they are doing. Flying level over central London at 3000' has me positively turning green with muscles rippling out of my shirt. Then the language comes.........
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Old 27th Jul 2008, 18:31
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being bigger and heavier and thus so much more effective
- personally I prefer the FT - the crossword is much 'harder'.

I'll raise your S/L Gell with a billiard cue in the back of the bonedome (Chipmunk)
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